Because health specialists have found that "washing your hands" can prevent so many illnesses beginning with the common cold...an idea might be to offer a motion-activated gadget that fits somewhere along the edge of an enterance (such as your front door) that auto-matically says "Welcome Home and remember to wash your hands"!  It could have a simple on-off button or switch in case the homeowner would like to turn it off for some reason?  Battery operation might be the way to go with something like this?

The Green Works logo can easily be adhered to the "gadget/thingy" (my technical term for the moment...LOL) and it could be offered FREE to those purchasing "X" number of Green Works products within a certain time period, killing two birds with one stone: offering a useful product and great advertising for Green Works too?